13F vs 13D vs 13G

The signal spectrum: passive → snapshot → active

Most plain-English guides describe these three filings in isolation — three bullet lists with different thresholds and deadlines. The problem with that framing is that it misses the point. The three filings are useful precisely because they sit on a spectrum of intent.

On one end you have 13G — "I own more than 5% of this company, but I'm not going to do anything about it." Index funds, pension funds, and qualified institutional investors file this. It tells you someone owns a big stake. It does not tell you they plan to move the stock price.

In the middle you have 13F — "Here is everything I own at the end of this quarter." It comes in late, 45 days after the quarter closed, and it bundles hundreds of positions together. No stated intent, no thresholds beyond the fund-level $100M floor. It's a quarterly portrait.

On the other end you have 13D — "I own more than 5%, and I'm planning to do something about it." This is the activist filing. It lands fast, in 10 days, and it requires the filer to state their intent. This is where you see language like "the reporting person intends to engage with the board" or "pursue strategic alternatives" — which is SEC-speak for "we're about to make noise."

Reading the three filings as a spectrum — not as three unrelated rules — is the difference between treating SEC data as a bureaucratic database and treating it as a live feed of investor intent.

What each filing actually contains

The three forms don't just differ in timing and threshold — they contain different information.

Schedule 13F includes a CUSIP list, ticker/issuer name, value (in thousands of dollars), share count, put/call designation for options, investment discretion (sole, shared, none), and voting authority. It excludes: short positions, cash, foreign-listed equities, fixed-income, most commodities, and derivatives that aren't exchange-traded options. You see only the long side. You see nothing about when inside the quarter they bought or sold, just the end-of-quarter snapshot. For a deeper walk-through see how to read a 13F filing in 5 minutes.

Schedule 13D contains a lot more. The filer's identity (including for each member of a group). The source and amount of funds used to acquire the stake. The purpose of the transaction — a narrative paragraph that legally binds the filer to their stated intent. Details of any agreements with other shareholders. Any past relationships with the company. And critically, any changes to the 13D require an amendment filing — so if activist intent escalates, there's a paper trail.

Schedule 13G is the short version. It contains the filer's identity and share count, but omits the purpose section. The filer is legally certifying that they do not intend to influence control of the company. If that changes, they must refile as 13D within 10 days.

The 5% threshold — and why it matters

Both 13D and 13G are triggered at 5% beneficial ownership of a class of voting securities. "Beneficial ownership" is broader than legal title — it includes shares over which the filer has voting or dispositive power, even indirectly. It also includes options and convertible securities exercisable within 60 days.

The 5% threshold exists because Congress decided, in the Williams Act of 1968, that a shareholder who owns enough stock to potentially swing a vote should be publicly disclosed. Before the Williams Act, hostile takeovers were often assembled in secret — a raider could accumulate 30% of a company's stock through dozens of brokerages before the company or existing shareholders had any idea what was happening. 13D was the fix: once you own 5%, the world knows.

In practice, this means 13D/G filings are not about portfolio disclosure — they are about corporate governance. A 13D is a governance event. A 13G is the routine paperwork that comes with being a big passive institution.

Timing — and why 13F is slowest

Speed matters. It's the second biggest difference between these filings after intent.

• 13D: 10 calendar days after crossing the 5% threshold. Amendments are required "promptly" — in practice, within days — after any material change in ownership or intent. This is the fastest SEC filing you'll encounter in this series.
• 13G: varies. Qualified institutional investors file within 45 days of year-end for stakes between 5% and 10%, and more frequently as ownership grows. Rule changes finalized in 2024 (effective 2025) shortened some of these windows. The key point: 13G is timing-driven by ownership size and class, not by a fixed event.
• 13F: 45 days after quarter end. A position established on the first day of a quarter may not surface in a 13F for up to 135 days. That's the 45-day lag — explained in detail in its own article.

This timing difference is what makes 13D filings useful as near-real-time signals — and 13F filings useful as longer-term portfolio views. They aren't substitutes. They answer different questions.

Who files what — the pattern-by-investor-type

If you look across the managers HoldLens tracks, you can spot the pattern of who reaches for which form.

• Activists (Carl Icahn, Bill Ackman when he's in activist mode, Dan Loeb, Nelson Peltz) are frequent 13D filers. For them, 13D is the opening move in a campaign. The filing itself is the signal — it's how they communicate to the market that a position matters and that engagement is coming.
• Concentrated value investors (Seth Klarman, Bill Ackman's Pershing Square for core long-term holds, Monish Pabrai) generally file 13F only, unless a stake crosses 5% — at which point they often file 13G for passive positions and only file 13D when they genuinely intend to engage.
• Diversified hedge funds (Druckenmiller, Tepper, Loeb's multi-strat book) file 13F but rarely hit 5% on any one name. Their positions are big in dollar terms, small as a percentage of the issuer.
• Index funds and quant houses (Vanguard, BlackRock, State Street, Renaissance at scale) are the 13G power users. They routinely own 5-15% of every S&P 500 component. They file the short-form 13G because they are categorically passive — their mandate prevents governance engagement.

Reading a manager's filing history tells you something about their strategy before you even look at the positions. A manager with frequent 13D amendments on a handful of names is playing a different game than a manager with 300 13F positions and zero 13Ds.

The 13G-to-13D switch is a major signal

One of the most useful patterns in SEC filings is the 13G-to-13D conversion.

When a filer originally certifies that their stake is passive and later decides to engage — push for a board seat, oppose a merger, advocate a spin-off, campaign for a CEO change — they are legally required to refile as Schedule 13D within 10 days. The switch is a public declaration that a previously passive position has turned active.

Market participants watch for this conversion because it often precedes material corporate events. A 13G-to-13D switch by a well-known activist can move a stock meaningfully in the session it's announced. The opposite direction — 13D filer voluntarily switching to 13G — is rarer but not unheard of, and it signals the filer has stood down.

13F data alone doesn't capture this. An activist's 13F will show the position quarter after quarter, but it won't mark the moment the intent changed. For that, you need the 13D/G feed.

How HoldLens uses each form

HoldLens is built on 13F data. That's the filing type that gives us quarterly portfolio snapshots across 30 superinvestors, enabling the ConvictionScore, the sector rotation maps, and the per-ticker dossiers you'll see on every manager page.

13D and 13G data are complementary but not yet in the core pipeline. For any single ticker, the 13D filings (if any) tell you which activist has a concentrated stake. The 13G filings tell you which big passive institutions are parked in the name. If you're studying a specific position, pulling those filings directly from EDGAR — SEC full-text search for the CUSIP — gives you a fuller governance picture that 13F alone can't.

For someone using HoldLens as a research starting point, the workflow that works best is: find a signal on HoldLens (a consensus buy, a conviction spike, a fresh 13F new-position), then go to EDGAR and check whether any 13D/G filings exist on the same name. The presence of an active 13D from a respected activist alongside a concentrated 13F position is a much richer signal than either alone.

What each filing does not tell you

Each form has its own blind spots. The blind spots matter as much as the content.

• 13F blind spots: no short positions, no cash, no derivatives beyond exchange-traded options, no foreign-listed securities, no intra-quarter trading, and no fund-level performance data. If a manager made a huge bearish bet via put options on a non-13(f) security, you'd never know from the 13F.
• 13D blind spots: only triggered at 5%. A manager who owns 4.9% of a company and is quietly advocating behind the scenes has no 13D obligation. The filing captures formal activist engagement, not informal conversations with management.
• 13G blind spots: the filer's declared passivity is a self-certification. In practice it's taken at face value until the filer switches to 13D — meaning a filer's stated intent and actual behavior can diverge for weeks before the paperwork catches up.

None of these blind spots make the filings useless. They just define the edges of what the data supports. Good analysis stays inside those edges.

Putting it together — a practical reading protocol

A workable mental model for using all three filings:

1. Start with 13F for the long-run view. Who owns what, with how much conviction, over which quarters. This is the HoldLens core data layer. It gives you the cast of characters.
2. Check 13D for activist layers. On any position that looks interesting, search EDGAR for Schedule 13D filings on the issuer. A live 13D from a respected activist changes the story. An amended 13D with escalating intent is a near-term catalyst.
3. Skim 13G to understand the passive float. Knowing that Vanguard and BlackRock together own 12% of a name doesn't tell you anything about the future, but it tells you who votes on the proxy — and that matters in any governance dispute.
4. Watch for 13G-to-13D conversions. The big signal. A filer who was passive is now active. Something has changed in their view of the company.

The broader SEC filing landscape

Schedules 13F, 13D, and 13G are not the only useful filings. Form 4 (insider trading disclosures), Form 10-K (annual reports), Form 10-Q (quarterly reports), and Form 8-K (material events) all contribute to the full picture. But the 13-series is the shareholder disclosure backbone — the forms that specifically answer the question "who owns this, and do they plan to do anything about it?"

Anyone serious about fundamental research should be comfortable reading all three. Most investors default to headlines and quarterly earnings calls. The shareholder filings are quieter, and they contain more signal per unit of noise than any other public source of financial information.

Further reading

• What is a 13F filing? — the foundational guide to the form HoldLens is built on.
• How to read a 13F filing in 5 minutes — step-by-step walkthrough using a real Berkshire example.
• The 45-day lag in 13F filings — why the quarterly window is six weeks late by design.
• What is a Conviction Score? — how HoldLens turns raw 13F data into a signed signal.
• Survivorship bias in hedge funds — why even 13F data gives you an overestimate of hedge fund performance, and what to do about it.
• The 30 tracked superinvestors — real 13F data on managers whose filings are worth reading.